package com.wontube.client.utils;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * @author yuechao
 * 
 */
public final class Base64 {
	private static final char[] base64EncodeChars = new char[] { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K',
			'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
			'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0',
			'1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' };

	private static final byte[] base64DecodeChars = new byte[] { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1,
			2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
			-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,
			-1, -1, -1, -1, -1 };

	private Base64() {
	}

	public static final String encode(byte[] data) {
		StringBuffer sb = new StringBuffer();
		int r = data.length % 3;
		int len = data.length - r;
		int i = 0;
		int c;
		while (i < len) {
			c = (0x000000ff & data[i++]) << 16 | (0x000000ff & data[i++]) << 8 | (0x000000ff & data[i++]);
			sb.append(base64EncodeChars[c >> 18]);
			sb.append(base64EncodeChars[c >> 12 & 0x3f]);
			sb.append(base64EncodeChars[c >> 6 & 0x3f]);
			sb.append(base64EncodeChars[c & 0x3f]);
		}
		if (r == 1) {
			c = 0x000000ff & data[i++];
			sb.append(base64EncodeChars[c >> 2]);
			sb.append(base64EncodeChars[(c & 0x03) << 4]);
			sb.append("==");
		} else if (r == 2) {
			c = (0x000000ff & data[i++]) << 8 | (0x000000ff & data[i++]);
			sb.append(base64EncodeChars[c >> 10]);
			sb.append(base64EncodeChars[c >> 4 & 0x3f]);
			sb.append(base64EncodeChars[(c & 0x0f) << 2]);
			sb.append("=");
		}
		return sb.toString();
	}

	public static final byte[] decode(InputStream in) throws IOException {
		ByteArrayOutputStream buf = new ByteArrayOutputStream();
		try {
			int b1, b2, b3, b4;
			int ch = in.read();

			while (ch != -1) {
				/* b1 */
				do {
					b1 = base64DecodeChars[ch];
					ch = in.read();
				} while (ch != -1 && b1 == -1);
				if (b1 == -1) {
					break;
				}

				/* b2 */
				do {
					b2 = base64DecodeChars[ch];
					ch = in.read();
				} while (ch != -1 && b2 == -1);
				if (b2 == -1) {
					break;
				}
				buf.write(((b1 << 2) | ((b2 & 0x30) >>> 4)));

				/* b3 */
				do {
					b3 = ch;
					if (b3 == 61) {
						return buf.toByteArray();
					}
					b3 = base64DecodeChars[b3];
					ch = in.read();
				} while (ch != -1 && b3 == -1);
				if (b3 == -1) {
					break;
				}
				buf.write((((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));

				/* b4 */
				do {
					b4 = ch;
					if (b4 == 61) {
						return buf.toByteArray();
					}
					b4 = base64DecodeChars[b4];
					ch = in.read();
				} while (ch != -1 && b4 == -1);
				if (b4 == -1) {
					break;
				}
				buf.write((((b3 & 0x03) << 6) | b4));
			}
			return buf.toByteArray();
		} finally {
			buf.close();
		}
	}

	public static final byte[] decode(String str) {
		ByteArrayInputStream bis = new ByteArrayInputStream(str.getBytes());
		try {
			return decode(bis);
		} catch (IOException e) {
		} finally {
			try {
				bis.close();
			} catch (IOException e) {
			}
		}

		return new byte[0];
	}
}
